1. Field of the Invention
The invention relates to a double-action hydraulic cylinder having in its cylinder barrel an axially slidable piston between a rear cover and a front cover whereby the piston may be coupled to an extreme load through a piston rod and whereby the piston may be biased via connections for a hydraulic medium at both sides with the hydraulic medium from an extreme pressure source. The invention additionally relates to an actuation arrangement for moving parts on vehicles, particularly for rear doors, trunk lids or engine covers, convertible tops or covers for convertible top storage compartments including at least one double-action hydraulic cylinder arranged between two vehicle components to be moved against one another, an extreme pressure source for the hydraulic medium, and a control unit.
2. The Prior Art
Various methods have been used for hydraulic cylinders to secure connections through which the hydraulic medium is supplied to the working chambers. These connections are in most cases welded to the cylinder barrel and at times there are studs provided that have borings, which are attached to the cylinder barrel by stud welding and onto which hydraulic hoses are fitted, possibly removable. These welded connections are often times not very good in their surface finish or their appearance and reliability, which is of importance especially during operation when the hydraulic cylinder becomes often visible, for instance in vehicles with automatically movable rear doors or trunk lids, convertible systems and the like.
The object of the present invention was therefore to provide a hydraulic cylinder that has a good surface finish and thereby also an optically appealing appearance together with a reliable mounting of the pressure medium connections. An additional object was to provide an actuation arrangement as described in the beginning, which offers these advantages as well.
To achieve the first object, the double-action hydraulic cylinder is characterized in that the connections are attached to the cylinder barrel by means of a soldered joint. This soldered joint guarantees, on one hand, great reliability of the mounting and, on the other hand, is advantageous in its appearance.
According to an additional characteristic of the invention, the connections are fitted on the cylinder barrel by means of a centering sleeve. During manufacturing, good temporary attachment of the connection to the cylinder barrel can be guaranteed and the transverse load on the connection is decreased thereby in the final product, which contributes additionally to the reliability of the chosen type of attachment.
A simple and rapid installation is achieved according to an additional characteristic of the invention in that the connections are provided with milled contact surfaces on the cylinder barrel.
To make a simpler and more economical production of hose connections possible, in another embodiment the connections are manufactured as a shaped piece having already a concave surface corresponding to the radius of the cylinder barrel, for instance in the form of an extrusion.
As a solution to the additional object, the actuation arrangement described in the beginning is characterized in that at least one of the hydraulic cylinders is designed according to the foregoing.
The invention will be explained in more detail in the following description with the aid of the accompanying drawings of illustrated embodiments.